"Among independent media groups her death caused uproar ... her writings were well known in Europe, the United Kingdom and the United States."

'Certain results'

Putin said last December that everything possible was being done to find and punish her killers.

"The best professionals in Russia's law enforcement are investigating this crime and we already have certain results," he said.

A prominent campaigner for press freedom expressed scepticism that prosecutors were any closer to convicting Politkovskaya's killers.

"The murders of journalists in the past 14 years have been so poorly investigated that it's hard to have any faith in this," Oleg Panfilov, head of the Centre for Journalism in Extreme Situations, told Reuters news agency.

"I suspect it's connected with the fact that the one-year anniversary of [her] death is coming up.

"People will ask 'Where are the killers?', and this way they can say that the case is closed and suspects have been detained."